Differential loop for heating systems



W. K. SIMPSON DIFFERENTIAL LOOP FOR HEATING SYSTES Oct. 7, 1930.

Filed Sept. 30,

`Patented Oct. 7, 193() UNITED STATES PATENT OFFICE WILLIAM IK. SIMPSON, OF WATERBURY, CONNECTICUT', ASSIGNOR T0 HOFFMAN SPE- --CIALTY COMPANY, OF WAT-RBURY, CONNECTICUT, A CORPORATION OF ILLINOIS DIFFERENTIAL LOOP FOR HEATING SYSTEMS Application led September 30, 1925i. Serial No. 59,537.

The present invention relates to automatic valveless pressure regulators for heating systems, designed and adapted to'permit transfer of steam from the steam line, or high pres- 'sure side of the system, to the return line, or low pressure side of the system, whenever V'the pressure in the boiler, or high pressure side, exceeds a predetermined value, while at the same time maintaining a diiierenceof pressure between the two sides of the system.

The object of the invention is to provide a regulator of a construction the parts of which may be simply and accurately made and assembled, and which can be installed readily in any system of the types to which it is applicable. f

The invention comprises the device and combination hereinafter particularly described, in the embodiment so described and in all equivalents thereof, within the scope of the appended claims.

Regulators 'of the type herein disclosed have been given the descriptive name of differential loop,7 in commercial practice; and I will use that same name in the following detailed description of my improved regulator.

In the drawings, y Figure l is adiagrammatic view showing a heating system equipped withmy differential loop.

Figure 2 is a vertical section of the loop apart from the system and shown on a larger scale.

Figure 3 is a cross section of the loop on line 3-3 of Figure 2.

' Referring first to Figure l in explanation of the utility of the invention and the environment in which it is used, the letter a designates a steam boiler, the letter b designates the steam supply pipe of a heatingsystem, c, c designate radiators, and CZ represents the return pipe. e represents-thermostatic return valves connected to the radiators and through which water of condensation and entrapped air are allowed to flow freely to the return pipe or line but which close automatically to prevent live steam so owing. p

frepresents my differential loop. It is connested by means of suitably arranged pipes g and L with the steam pipeor line, and thereby with the steam space of the boiler, and by means of a pipe z' with the return line. The steam line and steam space of the boiler constitute the high pressure side of the heating system, while the return line constitutes the low pressure side of the system.

Ashere shown, the return line runs from a high point near the boiler, on a gradual downward inclination in a circuit of the building in which the heating system is installed, 'and at a level wholly above the boiler water level, as far as a point j, also near the boiler. This part of the return `line normally is practically empty of water, containing only the condensate returning to theboiler, which'never fills it, and is vcalled the dry return. A descending pipe lc, connected to the dry return line at 7' and constituting what is called the Wet7 return line, carries the accumulated water of condensation to the boiler, and water normally rises therein to a height which will balance the boiler pressure. The loop is preferably connected to the high end of the return line. This layout of the return line, andthe idea of connecting the loop to the high end of such line are the invention. of Ralph R. Emerson of Brooklyn, N. Y., patented by him August 16, 1927, No. 1,639,084 and I do not claim them herein; but I have shown them as representing the best mode known to me of installing the loop, in which my invention resides, in a heating system.V

Referring now to Figures 2 and 3, which show the preferred structure 'of the loop in detail, such structure comprises a box or casing l0 having a partition l1 Whichdivides it into two chambers l2 and 13; upright pipes 14 and l5 secured to the casing in communication with openings in the bottoms of the chambers l2 and 13 respectively, and a coupling 16 joining the lower ends of said pipes. Generically, the loop as a whole is a U-tube, of which the pipes 14 and l5 are the legs, the coupling or tting 16 is the bottom, and the chambers l2 and 13 are the heads of the legs. The members or fittings thus designated as the easing l0 and coupling y16 may be made as castings of iron or other suitable metal, and the pipes 14 and 15 may be cast or drawn tubes threaded and screwed into the openings provided, substantially as shown, in the fittings and 16. The steam connection g is screwed into an entrance opening 17 in the top of theChamber 12, and the return line connectin fis screwed into an opening 18 in the side of the chamber 13.

rl ,`here is formed integral with the partition 11anV elbow conduit 19 which terminates within the chamber 12 in an orifice in substantially axial alineme'nt lwith the bottom opening which receives the pipe 14, and yto this elbow conduit there is attached, by being screwed into it,an interior pipe ,2,0 which extends 4downwardly in pipe 14`part way to the Ylower end of the latter. This pipe and the e1- bow litting 19 constitute an equalizi'ng pipe, sofcall'ed because it is adapted to perform an cqalizing function as presentlyV described.

"In the chamber 13 and opposite to the upper orifice of the elbow connection 19 is a curved baille 22 'which extends entirely across the chamber fromside to side and lies onan inclination between lthe connection 1.9 andthe "return line connection 18. Its purpose and effeet is to deect water issuing from the con- `nection 19 toward the pipe `15 and 4to prevent Outow of such water through the return Vline connection 18. Adjacent tothe upper end of l,thelbattle 22 is anopening 24 so arranged that steam flowing through theelbow connection may pass readily over the baille to the return line connection 18.

It'wi'll be noted that the coupling'or connection 1,6 between the lower ends ofthe pipes is partly blocked by a wall`25, and that there is a restricted passage 26ithrough said wall'. The chamber 13 has a connection 27 in its `upper Wall on which is mounted a' combination valve 28 containing a thermostatic outlet valveconstructed to pei-init outflow of air, but having a thermostat which closes the valve to .prevent outow of steam, a float which closes the valve to prevent outflow of water and a vacuum valve which closes to prevent ini-low oair when the pressure in the heating system drops below the atmospheric pressure. l

Vhen the loop is connected ina heating system as described, it conains water to a height at least sufficient to seal the lower end of the pipe 20. The water for this purpose may be poured into the loop before installation or it may be allowed to collect by condensation of steamv in the connection g and in the loop itself. At any rate while the system is in operation a suiiicient supply of water will be maintained by condensation to seal the pipe When the pressure in the boiler is higher than the return line pressure, the water level in the pipe 14 will be depressed and water will be transferred into the pipe until the difpipe 20. The absolute value :,Qfthis 4pressure diiflerence is determined by the vertical distance to whichtlhepip'e 20 descends below the level of the return line connection 18. N o niatterhowlhigh tlie boiler pressure may rise, the transfer of steam to the return line, which isfperiiiittcd by the loop,caus`es the return line Ppressure' to linderfroaparlallel rise, but the head of tiie water lcolumnl in pipe 15 `always maintains a pressure difference between the' boiler and the return line'.4

"Upon subsidence of the boiler pressure the Lfoinbifned` action of the `return line pressure and the pressure head in pipe 15 causes the watcij'lo rise in pipe l14 and seal the pipe 20 so'l'that steanican no longer pass through the loop until either. the boiler pressure rises againbr the `return line pressure is diminished by condensation of steam therein.

rdinaril'y itis intended that the systems in ifvhich the loop is used shall be operated with a boiler pressure not exceeding the water head capable of being created in the loop, siich water head being the prescribed maximum differential between theA boiler and the return line pressures; and when the system'iis thus operated, nosteam will pass Ithrough the loop, but the waterlevels in the twolegs thereof will assume positions such th'atthefeiifcess Ihead in leg '1 5 balances the boiler pressure. ,Only when abnormally high pressures occur inlthe boiler, or abnormally low pressures occurin the return line, will the loop allow steam to pass.V The pressure .then developed inthe return line by such transfer ot steam prevents anydangeriof water backing up intothe return line and so leaving the boiler. i

The theiniostatic v alve 28 being direct-ly contiguous tothe chamber 13 which is filled with steam as soon as steam begins to flow through the loop, is instantly closed by the steam then flowing, so'thatl the pressure in the" return line begins at once'to rise. But when air in the return line reaches the thern'lostatic valve,"or when the steam in the re turn line Condenses, this valve is opened, while'the associated vacuum valve will be openedfif there is air in the return line at a pressure higher than atmospheric, or remain closedif thereis aV vacuum in the return line. 4'The loop'v having the construction and characteristics abovedescribed, or the equivalent thereof, hasthe 'following features of advantage among others.V The baffle 22 preico vents water from leaving the loop when steam Hows through it. When the water in the pipe 14 is forced below the pipe 2O and steam enters the latter the steam has a strong tendency to pick up and carry water with it through the pipe 20, and it does thus carry a substantial quantity of water. But the water thus entrained, when discharged from the connection 19, strikes the baille 22 and is thereby deflected toward the pipe 15. At the same time the steam is allowed to pass through the opening 24, so that there is practically a complete separation between steam and water at this point. Such sepa-- ration is assisted by a narrow ledge 29 at the entrance to the steam passage 24. Steam, therefore, passes readily through the loop, but substantially all of the water is retained and preserved except that which, as a result of long accumulation, may pass by overflow through the return line connection. The important fact in connection with the batiie is, however, that it prevents water from being taken out of the loop by entrainment with steam, and so prevents the loop from becoming inoperative by loss of water.

The restriction 26 in the lower part of the loop retards the return flow of water from the leg 15 into the leg 14. The volume of flow through this restricted orifice is less than the volume of water which can be carried by entrainment with steam through the pipe 20. Thus immediately after the ilow of steam begins through pipe 20 the water level in the leg 14 is lowered to a point at which there is a minimum of entrainment, and it is maintained at such a low point until the increasing back pressure on the water column in pipe 15, acting in conjunction with the diminished flow of steam, causes the water in leg 14 to rise and again seal the pipe 20. In short, the restriction prevents the steam flow from setting up a circulation of water through the loop and diminishes the quantity of water required to be separated by the baiiie.

Vhat 1 claim and desire to secure by Letters Patent is:

1. A loop as and for the purposes set forth comprising a U-tube, a head having two chambers each connected with one of the legs of said tube, a steam connection to one of said chambers, an outlet connection from the other of said chambers, and an equaliz- 5 ing pipe extending within the upper part of that leg which is connected to the chamber having the steam connect-ion, said equalizing pipe being connected to discharge laterally into the other chamber.

2. A loop as and for the purposes set forth comprising a U-tube, a head having two chambers each separately connected with one of the legs of said tube, a steam connection to one of said chambers, an outlet conl nection from the other of said chambers, an

equalizing pipe extending within thev upper part of that' leg which is connected to the chamber having the steam connectiom said equalizing pipe being connected to discharge laterallyinto the other chamber, and a baffle in the last-named chamberwbetw'een the outlet of said equalizing pipe and the outlet from said chamber, to deflect water issuing from the equalizing pipe toward the, leg which is connected toy said last-named chamberl n 53; lAy loop as and for the purposes set forth comprising a head having an internal par-V tit'ion dividing` it into two chambers, legs forming a U-tube connected respectively to thefbottom parts of said chambers, oney of said chambers f having a steam connection and the otherhaving an outlet connection, an equalizing pipe located in one of said legs and opening'into the chamber which has said outlet'connection, and a battle in the latter chamber between said equalizing pipe outletand said outlet connection, with a steam passage between the highest part of thebaf-4 fie and the equalizing pipe outlet, anda water space lbeneath the batiieop'en tov the legV whichis connected to said last-named chamber; l

4. A differential loop` comprising a head, legs leading'v downward from said head, said head beinginternally divided into two chambers, oneA of which has a steam inlet andthe other an outlet, an equalizing pipe leading from'a relatively low point in that leg which is connected to the chamber having the steam inlet and arranged to discharge into the other chamber, and a loop bottom'connecting the lower ends of the legs and having a. restricted iiow passage ofless capacity than the water conducting capacity of said equalizing pipe. A Y

5. A dierential loop comprising legs connected together adjacent to their lower ends, 1

a steam connection to the head of one of said legs, a steam and water outlet connection to the head of t-he other leg, and an equalizing pipe opening at a low point in the leg rst above specified and leading thence to the head of the other leg, the connection between said legs having a flow capacity less than that of the equalizing pipe.

6. A differential loop comprising a leg adapted to be connected at its upper end with a steam source, a second leg having an outlet at its upper end, an equalizing pipe leading from t-he upper end of t-he second leg into the first leg and having an opening within said first leg at a level below said outlet, and a connection between the legs below the opening of the equalizing pipe having a flow capacity substantially less than that of the said pipe.

7 A differential loop comprising a leg adapted to be connected at its upper end with a steam source, a second leg having an llO outlet at its upper end, and equalizinglpipe lending from theupper end-of the-second leg into the first leg and having an opening within said first leg ate level `below said outlet, a baile in the seeondleg between said outlet and the point where theeqnalizing pipeopens into the leg arranged to separate water from steam issuing from the equalizing pipe, sind a connectionbetween the two legs at a 'point belowqthenopening of the equalizing pipe in the first leg having aow capacity less than that of .the ,eqnalizng Pipe- 8. A differential loopcomprising .an y11prightU-tube, a steam iniet tothe head'of one of the legs oaf said U-tube, a steamand water outlet from the head of the other leg of said U-tube, an erializingpipe leading from a low point in t e first leg/into the head of the other leg,.ra.nd means for separating water from steam issuing into the `second leg imm the .eualizing pipe.

9.; y,dierentialloopdcorriprising a head having an intermediate upright partition dividing it into two chambers, legs connected with' andy extending .downwardly from the bettom of the res ective `chambers and connected to each ot er near their lower ends, a conduit opening from one of said chambers and leading through the kether chamber downwardly jinto the ieg connected thereto and Vopening into such le ,end a bale crossing 1the first named cham er from a, point ad'jaoent'to but separated from and above the orifice ofsaid `conduit on a `downwrdand outward inclination Ytherefrom to-v wand the bottom of the chamber; saidy first chamber' hin-,ving an outlet ,and the second mentioned chamber havin-nr an inlet.

In rterstimany whereof have aixed'rny signature.

WILLIAM AK. SIMPSON. 

